Nuclear Theory·nucl-th

Friday·March 15, 2024

9 papers—3 primary·6 cross-listed

01
[Submitted on 14 Mar 2024]
Effects of neck and nuclear orientations on the mass drift in heavy ion collisions
Shota Amano · Yoshihiro Aritomo · Masahisa Ohta
We clarified that the fusion hindrance in heavy ion collisions is caused by the expansion of the neck bridge at the early stage of collision [Phys. Rev. C 108, 014612 (2023)]; however, our discussion was limited to the trajectory analysis. To get a reliable fusion cross section, it is important to understand the fusion process connecting with multinucleon transfer and also the process depending on the target orientation in detail. Especially, the effects of target orientation on the multinucleon transfer process have not been discussed so far in our model. First, we investigate precisely the start time of the neck expansion relevant to the mass transfer. The main aims of this paper are to discuss the mass drift in the collision with the different target orientations within the dynamical approach in the reaction 32S + 232Th. The orientation effects are incorporated within the framework of the Langevin equation. The start time of the neck expansion was presumed to be 10 zs by analysis in several entrance channels. By taking account of the target nuclear orientation, a strong mass-angle correlation was obtained which is compatible with the experimental data. Not only ``delayed relaxation'' of the neck but also the nuclear orientation effects have an important role in the strong correlation between fragment mass and its emitting angle. The mass evolution toward mass symmetry is slower than the standard mass drift mode assuming an exponential-type function. Particularly, the mass drift of the tip collision follows the slow mass drift mode assuming a Fermi-type function rather than an exponential-type function, which is related to the different features of the maximum neck cross-sectional area in the sticking process.
Comments:
Published in PRC on 11 March 2024. 13 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2403.09106 [pdf]
PRC(2024)·3 citations
02
[Submitted on 14 Mar 2024]
Femtoscopic study of the $Λ α$ interaction
Asanosuke Jinno🇯🇵 · Yuki Kamiya🇯🇵 · Tetsuo Hyodo🇯🇵 · Akira Ohnishi🇯🇵
We examine the $Λ$ - $^{4} He$ ( $α$ ) momentum correlation in high-energy collisions to elucidate the interaction between Lambdas ( $Λ$ ) and nucleons ( $N$ ). We compare phenomenological $Λ α$ potentials with different strengths at short range. In addition to the conventional Gaussian-type potentials, we construct the $Λ α$ potentials by substituting the nucleon density distribution in $α$ into the Skyrme-type $Λ$ potentials. We find that the dependence on the employed potential models is visible in the correlation functions from a small-size source. This indicates that the $Λ α$ momentum correlation could constrain the property of the $Λ N$ interaction at high densities, which is expected to play an essential role in dense nuclear matter. Also, we verify that the Lednicky-Lyuboshits formula can yield erroneous results for a small-size source with a potential which has a large interaction range, like the $Λ α$ system.
Comments:
8 pages, 6 figures, Published version in PRC, typos are fixed
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2403.09126 [pdf]
PRC(2024)·15 citations
03
[Submitted on 14 Mar 2024]
Detecting the third family of compact stars with normalizing flows
Valéria Carvalho🇵🇹 · Márcio Ferreira🇵🇹 · Constança Providência🇵🇹 · Michał Bejger🇵🇱
We explore the anomaly detection framework based on Normalizing Flows (NF) models introduced in \cite{PhysRevC.106.065802} to detect the presence of a large (destabilising) dense matter phase transition in neutron star (NS) observations of masses and radii, and relate the feasibility of detection with parameters of the underlying mass-radius sequence, which is a functional of the dense matter equation of state. Once trained on simulated data featuring continuous $M (R)$ solutions (i.e., no phase transitions), NF is used to determine the likelihood of a first-order phase transition in a given set of $M (R)$ observations featuring a discontinuity, i.e., perform the anomaly detection. Different mock test sets, featuring two branch solutions in the $M (R)$ diagram, were parameterized by the NS mass at which the phase transition occurs, $M_{c}$ , and the radius difference between the heaviest hadronic star and lightest hybrid star, $Δ R$ . We analyze the impact of these parameters on the NF performance in detecting the presence of a first-order phase transition. Among the results, we report that given a set of 15 stars with radius uncertainty of $0.2$ km, a detection of a two-branch solution is possible with 95\% accuracy if $Δ R > 0.4$ km.
Comments:
9 pages, 8 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2403.09398 [pdf]
PRD(2024)·4 citations
04
[Submitted on 12 Mar 2024] (cross-list from hep-ph)
On the resolution of the sign of gluon polarization in the proton
N. T. Hunt-Smith🇦🇺 · C. Cocuzza🇺🇸 · W. Melnitchouk🇺🇸 · N. Sato🇺🇸 · A. W Thomas🇦🇺 · M. J. White🇦🇺
Recently the possible existence of negative gluon helicity, $Δ g$ , has been observed to be compatible with existing empirical constraints, including from jet production in polarized proton-proton collisions at RHIC, and lattice QCD data on polarized gluon Ioffe time distributions. We perform a new global analysis of polarized parton distributions in the proton with new constraints from the high- $x$ region of deep-inelastic scattering (DIS). A dramatic reduction in the quality of the fit for the negative $Δ g$ replicas compared to those with positive $Δ g$ suggest that the negative $Δ g$ solution cannot simultaneously account for high- $x$ polarized DIS data along with lattice and polarized jet data.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2403.08117 [pdf]
PRL(2024)·20 citations
05
[Submitted on 13 Mar 2024] (cross-list from astro-ph.HE)
Collapsar disk outflows I: Viscous hydrodynamic evolution in axisymmetry
Coleman Dean · Rodrigo Fernández
We investigate mass ejection from accretion disks formed during the collapse of rapidly-rotating Wolf-Rayet stars. The neutrino-cooled, black hole (BH) accretion disk system that forms at the center of the star -- and the ensuing outflows -- provide the conditions for these systems to be candidate $r$ -process element production sites and potential progenitors of broad-lined Type Ic (Ic-BL) supernovae. Here we present global, long-term axisymmetric hydrodynamic simulations of collapsar disks that include angular momentum transport through shear viscosity, neutrino emission and absorption, a 19-isotope nuclear reaction network and nuclear statistical equilibrium solver, a pseudo-Newtonian BH with mass and spin modified by accreted matter, and self-gravity. Starting from a stellar profile collapsed in spherical symmetry, our models capture disk formation self-consistently, and are evolved until after the shock wave -- driven by disk winds -- reaches the surface of the star. None of our models achieve sufficient neutronization to eject significant amounts of $r$ -process elements (detailed nucleosynthesis calculations will follow in a companion paper). Sufficient $^{56}$ Ni is produced to power a typical type Ic-BL supernova light curve, but the average asymptotic velocity is a factor $\sim 2 - 3$ times too slow to account for the typical line widths in type Ic-BL supernova spectra. The gap in neutrino emission between BH formation and shocked disk formation, and the magnitude of the subsequent peak in emission, would be observable diagnostics of the internal conditions of the progenitor in a galactic collapsar. Periodic oscillations of the shocked disk prior to its expansion are also a potential observable through their impact on the the neutrino and gravitational wave signals.
Comments:
Accepted by PRD
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2403.08877 [pdf]
PRD(2024)·21 citations
06
[Submitted on 13 Mar 2024] (cross-list from hep-ph)
Hybrid analysis of radiative corrections to neutron decay with current algebra and effective field theory
Chien-Yeah Seng🇺🇸
We introduce a useful framework for high-precision studies of the neutron beta decay by merging the current algebra description and the fixed-order effective field theory calculation of the electroweak radiative corrections to the neutron axial form factor. We discuss the advantages of this hybrid method and show that it only requires a minimal amount of lattice QCD inputs to achieve a $1 0^{- 4}$ theory accuracy for the Standard Model prediction of the neutron lifetime and the axial-to-vector coupling ratio $λ$ , both important to the search for physics beyond the Standard Model.
Comments:
Version accepted by JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2403.08976 [pdf]
JHEP(2024)·12 citations
07
[Submitted on 14 Mar 2024] (cross-list from hep-ph)
Improved Constraints on the Variation of the Weak Scale from Big Bang Nucleosynthesis
Helen Meyer🇩🇪 · Ulf-G. Meißner🇩🇪
We present an improved calculation of the light element abundances in the framework of Big Bang nucleosynthesis as a function of the Higgs vacuum expectation value $v$ . We compare the methods of our calculation to previous literature including the recently published work of Burns et al. [1]. The PDG result for the $^{4}$ He abundance can be explained within $2 σ$ by $- 0.014 \leq δ v / v \leq 0.026$ , for deuterium we find the constraint $- 0.005 \leq δ v / v \leq - 0.001$ . These bounds are more stringent than what was found earlier.
Comments:
Now final version as published in JHEP
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2403.09325 [pdf]
JHEP(2024)·8 citations
08
[Submitted on 14 Mar 2024] (cross-list from hep-lat)
Curvature of the chiral phase transition line from the magnetic equation of state of (2+1)-flavor QCD
H.-T. Ding🇨🇳 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · P. Petreczky🇺🇸 · Mugdha Sarkar🇹🇼 · C. Schmidt🇩🇪 · Sipaz Sharma🇩🇪
We analyze the dependence of the chiral phase transition temperature on baryon number and strangeness chemical potentials by calculating the leading order curvature coefficients in the light and strange quark flavor basis as well as in the conserved charge ( $B, S$ ) basis. Making use of scaling properties of the magnetic equation of state (MEoS) and including diagonal as well as off-diagonal contributions in the expansion of the energy-like scaling variable that enters the parametrization of the MEoS, allows to explore the variation of $T_{c} (μ_{B}, μ_{S}) = T_{c} (1 - (κ_{2}^{B} μ^_{B}^{2} + κ_{2}^{S} μ^_{S}^{2} + 2 κ_{11}^{B S} μ^_{B} μ^_{S}))$ along different lines in the $(μ_{B}, μ_{S})$ plane. On lattices with fixed cut-off in units of temperature, $a T = 1/8$ , we find $κ_{2}^{B} = 0.015 (1)$ , $κ_{2}^{S} = 0.0124 (5)$ and $κ_{11}^{B S} = - 0.0050 (7)$ . We show that the chemical potential dependence along the line of vanishing strangeness chemical potential is about 10\% larger than along the strangeness neutral line. The latter differs only by about $3%$ from the curvature on a line of vanishing strange quark chemical potential, $μ_{s} = 0$ . We also show that close to the chiral limit the strange quark mass contributes like an energy-like variable in scaling relations for pseudo-critical temperatures. The chiral phase transition temperature decreases with decreasing strange quark mass, $T_{c} (m_{s}) = T_{c} (m_{s}^{phy}) (1 - 0.097 (2) (m_{s} - m_{s}^{phys}) / m_{s}^{phy} + O ((Δ m_{s})^{2})$ .
Comments:
19 pages, 11 figures, updated to published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2403.09390 [pdf]
PRD(2024)·44 citations
09
[Submitted on 14 Mar 2024] (cross-list from gr-qc)
Gravitational waves from glitch-induced f-mode oscillations in quark and neutron stars
Oliver H. Wilson (Haverford)🇺🇸 · Wynn C.G. Ho (Haverford)🇺🇸
Matter in compact stars is dense enough that transient events within the star could have sufficiently high energies to produce detectable gravitational waves (GWs). These GWs could be used to constrain the equation of state (EoS) for matter in the star and could reveal that there is more than one type of EoS at play in the population, implying that multiple types of compact stars exist. One of these types could be quark stars, composed almost entirely of stable quark matter, and observing GWs is a way to test for the strange matter EoS. Here we explore the possibility that, if fundamental (f-) mode oscillations in pulsars are induced by a pulsar glitch, then these oscillations might produce detectable GWs. We use the existing population of pulsars and their glitches, as well as a much larger synthesized population, along with 15 EoSs (8 for neutron stars and 7 for quark stars) to generate frequencies, damping times, and GW strengths for each. We find that of the EoSs examined, all quark star EoSs produce narrower distributions of f-mode frequency than neutron star EoSs. This result, along with other elements of the data, could be used to differentiate between GWs (or other signals from f-modes) originating from neutron stars and quark stars and thus could confirm the existence of quark stars. We also find that GW astronomy is a potentially viable method for detecting a larger population of pulsars which are not observable electromagnetically and that future GW observatories have the possibility to greatly expand this capability.
Comments:
12 pages, 16 figures; accepted for publication in Physical Review D
Subjects:
General Relativity and Quantum Cosmology (gr-qc); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2403.09489 [pdf]
PRD(2024)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE